Building materials

ABSTRACT

The present invention relates to building materials, particularly building materials for placement on the outside of buildings.

The present invention relates to building materials. In particular, the present invention relates to building materials for placement on the exterior of buildings. The present invention also relates to methods of producing such building materials.

Modern building methods call for a variety of building materials to inter alia suit aesthetic preferences and provide weather resistance over a number of years.

Various different materials have been used in the past to provide desired finishes to buildings. Common building materials include bricks and mortar for walls and slates for roofs. Metallic panels for exterior walls and/or tiles for roofs are now quite regularly used to provide hard wearing building materials which can come in a variety of colours. Panels and tiles can be provided with matching flashings and ancillaries to provide a desired finish. Examples of metallic panels are provided in the UK by Kingspan Benchmark™ and by KME™. In addition, Rockwool™ sell imitation metallic panels.

Vulcan Supply Corp.™ sell roofing products, e.g. roof tiles, which consist of copper. The copper is said to provide aesthetic properties to roofs, be waterproof and be environmentally friendly.

Although known metallic building materials, e.g. those mentioned above, stand up to strong weather conditions, they use a large amount of metal raw material. This results in high raw material cost, when compared to, for example, ceramic tiles, and generally high density, leading to higher transport costs, when compared to, for example, ceramic tiles. The inclusion of large amounts of metal raw material means that metallic building materials are heavy for their size, relative to plastic panels for example, because metals generally have a high density. Heavier panels for roofing, for example, place limits on design freedom in buildings, increases transportation costs and places tough limits on structures, e.g. with a particularly heavy roof walls would have to be thicker and foundations built to be more robust.

It would, therefore, be preferable to have building materials which provide the aesthetic and weather resistant properties of known metallic building materials, whilst using less metal.

U.S. Pat. No. 5,417,838 discloses the preparation of building panels, e.g. roofing panels, by placing a layer of copper over a preformed plastics structural base. The plastics structural base is generally an insulator. However, in one example the surface of the plastics structural base was subjected to an oxidising process by a high voltage corona discharge to render the surface conductive. The structural base was then placed in an electrodeposition bath and a thin layer of copper metal was deposited on the surface of the base.

Although U.S. Pat. No. 5,417,838 discloses the deposition of copper metal on a plastics structural base, the copper metal is a very thin layer and the panels produced are not suitable for most environments. In other words, the metal layers of the panels produced in U.S. Pat. No. 5,417,838 erode quickly to expose the plastics base layer because the plastics structural bases are poor conductors and have limited ability to electroplate. Additionally, the metal layer in the panels disclosed in U.S. Pat. No. 5,417,838 has a tendency to separate from the plastics structural base due to differences in coefficient of thermal expansion between the two materials.

In “filled resins”, coated with metallic layers, an insulating polymer provides a supporting role as the host material for conducting material, the conducting material being placed within holes in the host material. The conductivity is provided by a network of conductive particles, metal powders, graphite and/or carbon black to form an electrically conductive network.

“Filled resin” materials have very limited ability to electroplate effectively and the adhesion of the deposited metal to the thermoplastic substrate is weak; the surface and appearance finish are poor. This is because the insulating plastic on the surface has no electrical potential. Only the parts of the surface which are conductive have any electrical potential.

In a first aspect of the present invention, there is provided a building material, comprising:

-   -   a core comprising an intrinsically conductive polymer, and,     -   an outer layer, wherein the outer layer is metallic.

Preferably, wherein the outer layer surrounds the core.

Further preferably, wherein the outer layer partially surrounds the core.

Advantageously, wherein the intrinsically conductive polymer comprises an electrically conductive thermoplastic, a conductive thermoset plastic, a conductive elastomer, and/or a conductive polymer blend.

Preferably, wherein the intrinsically conductive polymer comprises any one or more of polydiacetylene, polyacetylene, polypyrrole, polyaniline, polythiophene, polyisothianaphthene, polyheteroarylenvinylene, where heteroarylene can be thiophene, furan or pyrrole, poly-p-phenylene, polyphenylene-sulphide, polyperinaphthalene, polyphthalocyanine, and their derivatives formed from monomers substituted with side chains or groups, or their copolymers.

Further preferably, wherein the core comprising a conductive polymer further comprises a non-conductive material.

Advantageously, wherein the intrinsically conductive polymer is filled and/or mixed with conductive particles.

Preferably, wherein the conductive particles are one or more of carbon black, graphite, graphene, carbon nanotubes and metal powders or fibers.

Further preferably, wherein the outer layer is zinc, copper, nickel, bronze, brass, solder, chrome, tin, lead, gold, silver and any other metallic metal or alloy, or combination of metallic metal and/or alloy, preferably, wherein the outer layer is copper.

Advantageously, wherein the building material is a panel, a facade panel, a rainscreen, a tile, a door, a fascia, a soffit, a weatherboard, a garage door, door furniture, fencing, a building detailing, a flashing, guttering, piping, a window frame or an ancillary of any shape and/or size for a particular building function.

In a further aspect of the present invention, there is provided a method of making a building material, for use on the exterior of a building, the building material comprising a core comprising an intrinsically conductive polymer, and, an outer layer, wherein the outer layer is metallic, wherein the method comprises:

-   -   forming a core comprising an intrinsically conductive polymer,         and,     -   electroplating the outer layer over the core.

Preferably, wherein the step of electroplating the outer layer over the core is by electrochemical means.

Further preferably, wherein the intrinsically conductive polymer is an electrically conductive thermoplastic, a conductive thermoset plastic, a conductive elastomer, or a conductive polymer blend.

Advantageously, wherein the intrinsically conductive polymer comprises any one or more of polydiacetylene, polyacetylene, polypyrrole, polyaniline, polythiophene, polyisothianaphthene, polyheteroarylenvinylene, where heteroarylene can be thiophene, furan or pyrrole, poly-p-phenylene, polyphenylene-sulphide, polyperinaphthalene, polyphthalocyanine, and their derivatives formed from monomers substituted with side chains or groups, or their copolymers.

Preferably, wherein the core comprising a conductive polymer is formed by a polymer manufacturing processes, preferably, compression moulding, extrusion, intrusion or injection moulding.

Further preferably, wherein the step of forming a core comprising a conductive polymer comprises the step of over moulding the conductive polymer over another material, optionally wherein the other material is a non-conductive polymer, further optionally wherein the step of over moulding includes bi-injection moulding and/or co-extrusion.

Advantageously, further comprising the step of, after forming the core and before electroplating the outer layer over the core, working the core so that it adopts a suitable shape.

Preferably, wherein electroplating the outer layer over the core by electrochemical means comprises:

-   -   placing the core in a solution of metal ions, the core being         configured to act as a cathode,     -   placing an anode comprising metal atoms, the metal atoms being         for the outer layer, in the solution, and,     -   providing a voltage across the core and the anode so that there         is a net movement of metal atoms from the anode to the cathode         to form the outer layer.

Further preferably, wherein the method comprises the further step of affixing a blocking structure to the core, prior to electroplating, so as to prevent formation of an outer layer at one or more positions on the core.

Advantageously, further comprising a washing step at any point.

Preferably, further comprising a working step after electroplating the core to work the outer layer into a desired shape.

In a further aspect of the present invention, there is provided a building material obtainable by a method according to any one of the above methods.

Embodiments of the invention are described below with reference to the accompanying drawings, in which:

FIG. 1 is a schematic representation of a building material according to the present invention.

FIG. 2 is a cross-section along line A-A of FIG. 1.

FIG. 3 is a schematic representation of a method of manufacturing a building material according to the present invention.

Referring to FIG. 1, a building material 1 is shown. In the embodiment shown in FIG. 1, the building material 1 is a tile which could be placed on a roof or on an external surface of a building. In other embodiments, the building material item could be a panel (optionally, a façade panel), a rainscreen, a tile, a door, a fascia, a soffit, a weatherboard, a garage door, door furniture, fencing, a building detailing, a flashing, guttering, piping, a window frame or an ancillary of any shape and/or size for a particular building function.

FIG. 2 shows the building material 1 in cross section along the line A-A. FIG. 2 shows that the building material 1 has a core 3 and an outer layer 2 surrounding the core 3. The core 3 comprises an intrinsically conductive polymer, for example an intrinsically conductive thermoplastic. The outer layer 2 is a metallic layer.

The term “intrinsically conductive polymer(s)” refers to organic polymers which have poly-conjugated it-electron systems (e.g. double bonds or aromatic rings). Examples of such polymers include, but are not limited to, polydiacetylene, polyacetylene, polypyrrole, polyaniline, polythiophene, polyisothianaphthene, polyheteroarylenvinylene (where heteroarylene can be thiophene, furan or pyrrole), poly-p-phenylene, polyphenylene-sulphide, polyperinaphthalene, polyphthalocyanine, and other known intrinsically conductive polymers, and their derivatives (formed for example from monomers substituted with side chains or groups), their copolymers and their physical compounds. They can exist in various states, each described by different empirical formulae, which can generally be converted reversibly into one another by electrochemical reactions such as oxidation, reduction, acid/alkali reaction or complexing. These reactions are also occasionally known as “doping” or “compensation” in the art, or can be regarded as “charging” and “discharging” in analogy with the electrochemical processes in batteries. At least one of the possible states is a very good conductor of electricity, e.g. has a conductivity of more than 1 Siemens/cm (in pure form).

In one embodiment, the intrinsically conductive polymer of the core 3 may be over-moulded over another polymer or material, which may not be electrically conductive. In this embodiment, the core 3 is formed by initially forming a composite part from a first polymer and/or other generally inert material, e.g. a non-electrically conductive polymer (which may be relatively cheaper and/or lighter than the electrically conductive polymer, e.g. epoxy resin, expanded polystyrene, polymer foams) and/or glass materials, and subsequently forming the intrinsically conductive polymer over the composite part formed of the first polymer.

Examples of metals and alloys which in different embodiments make up the outer layer 2 include zinc, copper, nickel, bronze, brass, solder, chrome, tin, lead, gold, silver and any other metallic metal or alloy, or a combination of metallic metal and/or alloy.

The presence of the core 3 reduces the amount of metal required in the building material item 3, as compared with building materials made entirely of metal.

The building material 1 can, in one embodiment, be made by a method as discussed with reference to FIG. 3.

FIG. 3 shows electroplating of a metallic outer layer 2 on top of a core 3, the core 3 being made of an intrinsically conductive polymer, for example, but not limited to, polydiacetylene, polyacetylene, polypyrrole, polyaniline, polythiophene, polyisothianaphthene, polyheteroarylenvinylene (where heteroarylene can be thiophene, furan or pyrrole), poly-p-phenylene, polyphenylene-sulphide, polyperinaphthalene, polyphthalocyanine, and other known intrinsically conductive polymers, and their derivatives (formed for example from monomers substituted with side chains or groups), their copolymers and their physical compounds. The core 3 of intrinsically conductive polymer can be made by known polymer manufacturing processes, such as compression moulding, extrusion, intrusion or injection moulding. Using these known processes, the core 3 can be shaped for its desired function. Alternatively, in other non-limiting embodiments, the core 3, comprising an intrinsically conductive polymer and a separate composite part formed of another material can be formed together by bi-injection or co-extrusion.

In FIG. 3, the cathode is the core 3. The anode 4 is a metallic element made up of metal atoms which are to be layered on top of the core 3. The cathode and the anode 4 are both connected to an external supply of direct current 5, e.g. a battery or a rectifier. The anode 4 is connected to the positive terminal of the external supply of direct current 5 and the cathode is connected to the negative terminal. When the external supply of direct current 5 is turned on, the metal at the anode is oxidised to form cations which have a positive charge and go into the solution 6, which has a meniscus 7. The cations M^(n+) associate with anions A^(n−) in solution. The cations are reduced at the cathode and deposit in the metallic state. In other words, by way of this electroplating process, a metallic outer layer 2 forms over the core 3.

In the above process, the cathode can be made from any intrinsically conductive polymer, e.g. intrinsically conductive thermoplastics. Particularly preferred examples of intrinsically conductive thermoplastics include, but are not limited to, polymers currently on the market and sold by Cool Polymers®, Inc. as their E-series polymers, such as E2, E4501, E4505 and E5101.

The intrinsically conductive polymer of the core can be selected to match the thermal expansion coefficient of the metal which is deposited on and/or over the core. For example, the co-efficient of thermal expansion of E4505 is 33 ppm/° C. Metallic zinc has a similar co-efficient of thermal expansion at 30 ppm/° C. Therefore, a core comprising E4505 and an outer layer of zinc is a particularly preferred example. Using insulating polymers, or insulating polymers comprising conduction portions, the thermal expansion coefficient of the core is often between two or three times the thermal expansion coefficient of most metals, e.g. zinc and copper. It is preferable for the co-efficient of thermal expansion of the core and the metallic outer layer to be the same, or at least a similar co-efficient of thermal expansion within 20,10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 ppm/° C. By selecting materials for the core and the metallic outer layer so that they have a similar co-efficient of thermal expansion, the risk of catastrophic failure is minimised because the bond between the core and the metallic outer layer is put under minimal strain under different temperature conditions.

Other examples of combinations of intrinsically conductive polymers, coated with a metallic layer and for use in building materials, include, but are not limited to:

-   -   Cool Polymers®, Inc.'s Coolpoly E2 (which has a linear         co-efficient of thermal expansion of 9.1 ppm/° C.) electroplated         with nickel (which has a linear co-efficient of thermal         expansion of 13 ppm/° C.).     -   Cool Polymers®, Inc.'s Coolpoly E5101 (which has a linear         co-efficient of thermal expansion of 14 ppm/° C.) electroplated         with copper (which has a linear co-efficient of thermal         expansion of 17 ppm/° C.).

In an alternative embodiment, the core 3 mentioned above can additionally include injection moulding metal powders, particles or fibers, and/or graphene, to make an intrinsically conductive polymer and metal blend or matrix. Examples of injection moulding metal powders include, but are not limited to, bronze granules and flake metal copper powder (e.g. type 2500, as currently sold by AVL Metal Powders NV, Kortrijk, Belgium). In other non-limiting examples, the injection moulding metal powders include stainless steel fibres, particles or powders (e.g. Advanced Metalworking Practices, LLC product range ADVAMET®). When using stainless steel, the passive oxide film of the stainless steel exposed on the surface of the thermoplastic matrix must be cleaned by chemical cleaning and activation processes, such as nickel strike, chloride pre cleaning, e.g. Zinc chloride or copper chloride strikes.

In the above process, the anode can be made from any metal or alloy, i.e. an alloy which can undergo the electroplating process, from which it is desired to form the outer layer 2 over the core 3. Examples of metals and alloys which can form the anode include, but are not limited to, zinc, copper, nickel, bronze, brass, solder, chrome, tin, lead, gold, silver and any other metallic metal or alloy, or combination of metallic metal and/or alloy.

In the above process, the solution 6 contains a dissolved mixture of metallic salt which is complementary to the metal forming the anode 4. For example, when the anode is copper, the solution 6 can be a solution of CuSO₄, so the anion, A^(n−), is SO₄ ²⁻ and the copper ions in solution are Cu²⁺. Another example, when the anode is zinc, the solution 6 can be a solution of ZnSO₄, so the anion, A^(n−), is SO₄ ²⁻ and the zinc ions in solution are Zn²⁺. Another example, when the anode is nickel, the solution 6 can be a solution of NiSO₄, so the anion, A^(n−), is SO₄ ²⁻ and the nickel ions in solution are Ni²⁺.

As with known electroplating processes, the anode is often of the same metal to be deposited but not always. The anode can consist of a non-consumable alternative metal. For example, lead can be used as the anode when it is desired to reduce the g/l of copper content in the copper plating solution. In another example, tin-lead alloy anodes can be employed for chromium plating, for example with chrome flakes directly added according to the usage of the bath as opposed to a reduction of the anode.

Generally, the intrinsically conductive polymer which makes up the core 3 is selected to allow sufficient electrodeposition of the chosen metal or alloy. The conductive polymer will have an electrical resistance of 10000 per square or less, including each and every integer below 10000 per square, preferably an electrical resistance of 400 per square or less. The units of Ω per square are commonly used when referring to sheet resistance. Referring to sheet resistance as simply Ω could be taken out of context and misinterpreted as bulk resistance.

Electroplating can be carried out using reverse pulse plating to reduce the effect of intrinsically conductive polymers' electrical resistance on the current density during electroplating.

In the example shown in FIG. 3, only part of the core 3 is shown in the solution 6. In a preferred embodiment, the whole of the core 3 is covered with the metallic outer layer 2. In other embodiments, only part of the core 3 is covered with the metallic outer layer 2, e.g. only the part of the building material 1 which is to be exposed to the elements when the building material is in use.

An alternative method of covering the core with a metal and/or alloy is by way of electroless plating. Electroless plating is an auto-catalytic process for depositing a metal and/or alloy on an object, for example, a plastic object. Electroless plating utilises a reducing agent to react with metal ions in solution to deposit metal on the object.

The building materials according to the present invention provide building materials with similar wear properties to known metallic building materials with at least the advantage that the building materials of the present invention use less raw metallic material. This saves on raw material cost and also reduces the weight of the building materials, thereby reducing, for example, transportation cost.

The building materials according to the present invention provide building materials with thicker metallic layers over the core than previous building materials formed by electrodeposition over a generally insulating polymeric core after the core has been subjected to an oxidising process to render the surface at least partially conductive. After subjecting a generally insulating polymeric core to an oxidising process, the core is weakly conducting so only a very thin layer of metal can be economically deposited. Furthermore, the metallic layer formed on a generally insulating core after the generally insulating polymeric core has been oxidised is only weakly attached and is more akin to electroforming, where a metallic layer can be formed on a surface by mechanical (e.g. by screws or bolts), or adhesive (e.g. glue), means.

When used in this specification and claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. 

1. A building material, comprising: a core comprising an intrinsically conductive polymer, and, an outer layer, wherein the outer layer is metallic.
 2. The building material of claim 1, wherein the outer layer surrounds the core.
 3. The building material of claim 1, wherein the outer layer partially surrounds the core.
 4. The building material of claim 1 wherein the intrinsically conductive polymer comprises an electrically conductive thermoplastic, a conductive thermoset plastic, a conductive elastomer, and/or a conductive polymer blend.
 5. The building material of claim 1, wherein the intrinsically conductive polymer comprises any one or more of polydiacetylene, polyacetylene, polypyrrole, polyaniline, polythiophene, polyisothianaphthene, polyheteroarylenvinylene, where heteroarylene can be thiophene, furan or pyrrole, poly-p-phenylene, polyphenylene-sulphide, polyperinaphthalene, polyphthalocyanine, and their derivatives formed from monomers substituted with side chains or groups, or their copolymers.
 6. The building material of claim 1, wherein the core comprising a conductive polymer further comprises a non-conductive material.
 7. The building material of claim 4, wherein the intrinsically conductive polymer is filled and/or mixed with conductive particles.
 8. The building material of claim 7, wherein the conductive particles are one or more of carbon black, graphite, graphene, carbon nanotubes and metal powders or fibers.
 9. The building material of claim 1, wherein the outer layer is zinc, copper, nickel, bronze, brass, solder, chrome, tin, lead, gold, silver or other metallic metal or alloy, or combination of metallic metal and/or alloy.
 10. (canceled)
 11. A method of making a building material, for use on the exterior of a building, the building material comprising a core comprising an intrinsically conductive polymer, and, an outer layer, wherein the outer layer is metallic, wherein the method comprises: forming a core comprising an intrinsically conductive polymer, and, electroplating the outer layer over the core.
 12. The method of claim 11, wherein the step of electroplating the outer layer over the core is by electrochemical means.
 13. The method of claim 11, wherein the intrinsically conductive polymer is an electrically conductive thermoplastic, a conductive thermoset plastic, a conductive elastomer, or a conductive polymer blend.
 14. The method of claim 11, wherein the intrinsically conductive polymer comprises any one or more of polydiacetylene, polyacetylene, polypyrrole, polyaniline, polythiophene, polyisothianaphthene, polyheteroarylenvinylene, where heteroarylene can be thiophene, furan or pyrrole, poly-p-phenylene, polyphenylene-sulphide, polyperinaphthalene, polyphthalocyanine, and their derivatives formed from monomers substituted with side chains or groups, or their copolymers.
 15. The method of claim 11, wherein the core comprising a conductive polymer is formed by compression moulding, extrusion, intrusion or injection moulding.
 16. The method of claim 11, wherein the step of forming a core comprising a conductive polymer comprises the step of over moulding the conductive polymer over another material.
 17. The method of claim 11, further comprising the step of, after forming the core and before electroplating the outer layer over the core, working the core so that it adopts a suitable shape.
 18. The method of claim 11, wherein electroplating the outer layer over the core by electrochemical means comprises: placing the core in a solution of metal ions, the core being configured to act as a cathode, placing an anode comprising metal atoms, the metal atoms being for the outer layer, in the solution, and, providing a voltage across the core and the anode so that there is a net movement of metal atoms from the anode to the cathode to form the outer layer.
 19. The method of claim 11, wherein the method comprises the further step of affixing a blocking structure to the core, prior to electroplating, so as to prevent formation of an outer layer at one or more positions on the core.
 20. (canceled)
 21. The method of claim 11, further comprising a working step after electroplating the core to work the outer layer into a desired shape.
 22. A building material obtainable by a method according to claim
 11. 23.-24. (canceled) 